include/asm-sh/semaphore.h

   1 #ifndef __ASM_SH_SEMAPHORE_H
   2 #define __ASM_SH_SEMAPHORE_H
   3
   4 #include <linux/linkage.h>
   5
   6 #ifdef __KERNEL__
   7 /*
   8  * SMP- and interrupt-safe semaphores.
   9  *
  10  * (C) Copyright 1996 Linus Torvalds
  11  *
  12  * SuperH verison by Niibe Yutaka
  13  *  (Currently no asm implementation but generic C code...)
  14  */
  15
  16 #include <linux/spinlock.h>
  17 #include <linux/rwsem.h>
  18 #include <linux/wait.h>
  19
  20 #include <asm/system.h>
  21 #include <asm/atomic.h>
  22
  23 struct semaphore {
  24         atomic_t count;
  25         int sleepers;
  26         wait_queue_head_t wait;
  27 };
  28
  29 #define __SEMAPHORE_INITIALIZER(name, n)                                \
  30 {                                                                       \
  31         .count          = ATOMIC_INIT(n),                               \
  32         .sleepers       = 0,                                            \
  33         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  34 }
  35
  36 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  37         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  38
  39 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  40
  41 static inline void sema_init (struct semaphore *sem, int val)
  42 {
  43 /*
  44  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  45  *
  46  * i'd rather use the more flexible initialization above, but sadly
  47  * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
  48  */
  49         atomic_set(&sem->count, val);
  50         sem->sleepers = 0;
  51         init_waitqueue_head(&sem->wait);
  52 }
  53
  54 static inline void init_MUTEX (struct semaphore *sem)
  55 {
  56         sema_init(sem, 1);
  57 }
  58
  59 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  60 {
  61         sema_init(sem, 0);
  62 }
  63
  64 #if 0
  65 asmlinkage void __down_failed(void /* special register calling convention */);
  66 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  67 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  68 asmlinkage void __up_wakeup(void /* special register calling convention */);
  69 #endif
  70
  71 asmlinkage void __down(struct semaphore * sem);
  72 asmlinkage int  __down_interruptible(struct semaphore * sem);
  73 asmlinkage int  __down_trylock(struct semaphore * sem);
  74 asmlinkage void __up(struct semaphore * sem);
  75
  76 extern spinlock_t semaphore_wake_lock;
  77
  78 static inline void down(struct semaphore * sem)
  79 {
  80         might_sleep();
  81         if (atomic_dec_return(&sem->count) < 0)
  82                 __down(sem);
  83 }
  84
  85 static inline int down_interruptible(struct semaphore * sem)
  86 {
  87         int ret = 0;
  88
  89         might_sleep();
  90         if (atomic_dec_return(&sem->count) < 0)
  91                 ret = __down_interruptible(sem);
  92         return ret;
  93 }
  94
  95 static inline int down_trylock(struct semaphore * sem)
  96 {
  97         int ret = 0;
  98
  99         if (atomic_dec_return(&sem->count) < 0)
 100                 ret = __down_trylock(sem);
 101         return ret;
 102 }
 103
 104 /*
 105  * Note! This is subtle. We jump to wake people up only if
 106  * the semaphore was negative (== somebody was waiting on it).
 107  */
 108 static inline void up(struct semaphore * sem)
 109 {
 110         if (atomic_inc_return(&sem->count) <= 0)
 111                 __up(sem);
 112 }
 113
 114 #endif
 115 #endif /* __ASM_SH_SEMAPHORE_H */